Up to 60% of White adults diagnosed with a deadly form of skin cancer in the United States may not need aggressive treatment, a study published Wednesday by JAMA Dermatology found.
The findings suggest that efforts to encourage screening for melanoma, a less common form of skin cancer that is more likely to spread and become life-threatening, may have resulted in "overdiagnosis" of the disease nationally, the researchers said.
This means people diagnosed with the cancer at its early stages may not see their tumors spread, cause symptoms or lead to death, even without treatment, according to the researchers.
"Overdiagnosis is caused by increasing skin cancer screening in the general population, increases in the rate of skin biopsies and lower thresholds that pathologist label skin biopsy specimens as cancer," study co-author Dr. Adewole S. Adamson told UPI in an email.
"Our study estimates that a significant proportion of these early melanomas are likely overdiagnosed, meaning if left alone they would never have caused symptoms or death in a patient's lifetime," said Adamson, an assistant professor of dermatology at the University of Texas at Austin.
Melanoma is the deadliest form of skin cancer, and it occurs when the pigment-making cells in the skin, called melanocytes, begin to reproduce uncontrollably, according to Harvard Medical School.
The cancer can form from an existing mole or develop on unblemished skin, and it usually spreads on the surface of the skin.
After a rise in cases of the potentially deadly cancer in the 1970s in the United States, efforts were made to increase public awareness of and screening for the disease, Adamson and his colleagues said.
As a result, more cases of melanoma were identified in their early stages, leading to more aggressive treatment and reduced deaths, the researchers said.
Between 1975 and 2014, the number of melanomas diagnosed in the United States increased four-fold among White women and six-fold among White men, the data showed.
Among Black men and women over the same period, melanoma diagnoses increased by just under 25%, the researchers said.
During this 40-year period, due at least in part to improvements in treatment, deaths from melanoma decreased approximately 25% in Black women and men and "remained stable" in White women, according to the researchers.
However, they increased by nearly 50% in White men, the data showed.
These apparent "discrepancies" between diagnosis and death trends suggest that at least some of these cancers may not have needed aggressive, or earlier, treatment, the researchers said.
Though improved treatment prevented death in up to 40% of diagnosed cases, an estimated 59% of White women and 60% of White men with melanoma were overdiagnosed in 2014, according to the researchers.
Overdiagnosis was not as significant a problem among Black women and men, they said.
"Since we do not know which early cancers are destined to progress, we treat all of them," Adamson said.
Based on these findings, "one thing I would advise patients is to discuss with their dermatologist whether or not skin cancer screening is recommended for them," he said.